This invention relates generally to a wide variety of structures and devices formed of layers of materials and more particularly, to systems, devices, arrangements, coatings, and a variety of other items which utilize layered structures, particularly quasi-periodic layered structures.
Layered structure arrangements find application in a vast array of devices and systems throughout a variety of technical disciplines. For example, a variety of electronic components and microcircuit systems are formed by applying plural layers of semiconductor material. Similarly, such layering is commonly used in the production of photoconductive devices and optical devices, such as lenses, particularly coatings therefor, mirrors, optical filters, and fiber optic cladding.
It is well known that the response characteristic of layered devices depend to a substantial extent upon the arrangement of the layers as a sequence, the thickness of the layers, and the composition of the layers. It is known that a variety of desirable device characteristics may be achieved if a non-periodic, or quasi-periodic layering arrangement could be effected. For example, in the electronic devices field, quasi-periodic layering of semiconductor materials may be useful in achieving negative differential resistance effects. In the field of optics, the use of quasi-periodic layering arrangements on lenses, mirrors, and filters may result in advantageous optical characteristics, in preselected spectral regions. For example, a power law frequency response characteristic may be achieved with the use of such quasi-periodic layering.
In the field of optics, there is a need for a versatile coating system which can be tailored to specific needs. The present state of this technology, for electromagnetic surface coatings, is based on homogeneous layers of precisely controlled thickness, or on multiple layers which are deposited in a periodic fashion. These known configurations limit the performance efficiency of the resulting device and limit the operating range to narrow bandwidths. Such limitations are particularly severe in the X-ray and hard ultraviolet region of the spectrum. There is currently no satisfactory general solution to the problem of fabricating high efficiency X-ray mirrors and other components at these frequencies.
It is, therefore, an object of this invention to provide a simple and economical system for achieving the advantages of quasi-periodic structures.
It is another object of this invention to provide a system having selectable surface properties.
It is also an object of this invention to provide a coating system having a tailorable electromagnetic response characteristic.
It is a further object of this invention to provide a coating system which is less sensitive than known arrangements to defects and irregularities.
It is additionally an object of this invention to provide a thin film structure having a characteristic with a very high density of Fourier peaks.
It is yet another object of this invention to provide a quasi-periodic arrangement of optical layers.
It is still a further object of this invention to provide a quasi-periodic arrangement of metallic layers.
It is also another object of this invention to provide a quasi-periodic arrangement of semiconductor layers.
It is also an additional object of this invention to provide a quasi-periodic arrangement of dielectric layers.
It is yet a further object of this invention to provide a quasi-periodic arrangement of transparent oxides.
It is still another object of this invention to provide a multilayer coating which exhibits quasi-periodic characteristics formed by molecular beam epitaxy.
Another object of this invention is to provide a multilayer coating exhibiting quasi-periodic characteristics formed by sputtering.
A further object of this invention is to provide a multilayer coating exhibiting quasi-periodic characteristics formed by chemical vapor deposition.
An additional object of this invention is to provide a multilayer coating exhibiting quasi-periodic characteristics formed by liquid phase epitaxy.
Still another object of this invention is to provide a multilayer coating exhibiting quasi-periodic characteristics formed by aerosol coating.
A yet further object of this invention is to provide a multilayer device characterized by power law behavior.